The telephone answering system described in the copending application includes an announcement tape which is activated during an announcement interval (T.sub.1) in response to a telephone call, and which causes a recorded announcement on the announcement tape to be transmitted over the telephone line to the calling party during that interval. At the end of the announcement interval (T.sub.1), a message tape is activated, and it records the message from the calling party during an ensuing time interval (T.sub.2). The telephone answering system may be constructed so that the time interval (T.sub.2) may have a predetermined fixed time duration, or so that the time interval (T.sub.2) may continue, within the limits of the system, for as long as the calling party is transmitting his message.
The telephone answering system described in the copending application enables the user of the system to call in from any part of the world, and to activate the system and cause it to transmit to the caller all the accumulated messages on the message tape. As fully described in U.S. Pat. No. 3,757,049, which issued Sept. 4, 1973, and which is assigned to the present assignee, remote control of the telephone answering system may be achieved by means of a small portable transmitter unit which is held up by the caller to the mouthpiece of a telephone, and which is pushbutton controlled to transmit a tone signal of a predetermined frequency over the telephone line. The telephone answering system is designed to respond to the particular tone frequency to activate a remote control circuit therein, so that the message tape may be rewound to its origin position, and then set to a playback condition so that the messages on the tape may be successively transmitted over the telephone line to the calling party.
The present invention provides a telephone answering system which incorporates a simple remote control circuit that responds to a tone signal of a particular frequency received over the telephone line. The control circuit of the invention, in response to the received tone signal, causes the message tape to return to its origin position, and then automatically sets the telephone answering system to its playback mode, so that the messages on the message tape may be transmitted in sequence to the calling party over the telephone line. The remote control circuit of the invention then responds to a second tone signal of the same frequency transmitted over the telephone line by the calling party to terminate the playback operation after the last message has been transmitted, and to reset the telephone answering system to its automatic answer operational mode.